Compressed air injection system method and apparatus for gas turbine engines

ABSTRACT

This invention relates to electrical power systems, including generating capacity of a gas turbine, and more specifically to augmentation of power output of gas turbine systems, that is useful for providing additional electrical power during periods of peak electrical power demand.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/686,222, filed Apr. 2, 2012, hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates generally to gas turbine power systems, includingsupplementing the generating capacity of such gas turbines, as well asto energy storage, that is useful for providing additional electricalpower during periods of peak electrical power demand while selfconsuming power generated by the gas turbine during times of reducedpower demand.

BACKGROUND OF THE INVENTION

Currently, marginal energy, or peak energy, is produced mainly by gasturbines, operating either in simple cycle or combined cycleconfigurations. As a result of load demand profile, the gas turbine basesystems are cycled up during periods of high demand and cycled down, orturned off, during periods of low demand. This cycling is typicallydriven by the electrical grid operator under a program called “activegrid control”, or AGC. Unfortunately, because industrial gas turbines,which represent the majority of the installed power generation base,were designed primarily for base load operation, a severe penalty isassociated with the maintenance cost of that particular unit when theyare cycled. For example, a gas turbine that is miming base load might gothrough a normal maintenance cycle once every three years, or 24,000hours of operation, at a cost of between two million dollars and threemillion dollars ($2,000,000 to $3,000,000). That same cost could beincurred in one year for a gas turbine that is forced to start up andshut down every day due to the severe penalty associated with themaintenance cost of cycling that particular gas turbine. Also, evenaero-derivative engines, which are designed for quick startingcapability, may still take ten (10) minutes or longer to deliver therequired power when called on. This need to cycle the gas turbine fleetis a major issue, and is becoming more problematic with the increaseduse of intermittent renewable energy sources on the grid.

Currently the gas turbine engines used at power plants can turn down toapproximately 50% of their rated capacity. They do this by closing theinlet guide vanes of the compressor, which reduces the air flow to thegas turbine and in turn reduces fuel flow, as a constant fuel air ratiois desired in the combustion process at all engine operating conditions.The goal of maintaining safe compressor operation and gas turbineexhaust emissions typically limit the level of turn down that can bepractically achieved.

One way to safely lower the operating limit of the compressor in currentgas turbines is by introducing warm air to the inlet of the gas turbine,typically extracted from a mid-stage bleed port on the compressor.Sometimes, this warm air is introduced into the inlet to prevent icingas well. In either case, when this is done, the work that is done to theair by the compressor is sacrificed in the process for the benefit ofbeing able to operate the compressor safely at a lower air flow,yielding the increased turn down capability. Unfortunately, bleeding airfrom the compressor has a further negative impact on the efficiency ofthe overall gas turbine system as the work performed on the air that isbled off is lost. In general, for every 1% of air that is bled off thecompressor for this turn down improvement, approximately 2% of the totalpower output of the gas turbine is lost. Additionally, the combustionsystem also presents a limit to the system.

The combustion system usually limits the amount that the system can beturned down because as less fuel is added, the flame temperaturereduces, increasing the amount of carbon monoxide (“CO”) emissionsproduced. The relationship between flame temperature and CO emissions isexponential with reducing temperature, consequently, as the gas turbinesystem gets near the turn-down limit, the CO emissions spike up, so itis important to a maintain a healthy margin from this limit. Thischaracteristic limits all gas turbine systems to approximately 50% turndown capability, or, for a 100 MW gas turbine, the minimum powerturn-down that can be achieved is about 50%, or 50 MW. As the gasturbine mass flow is turned down, the compressor and turbine efficiencyfalls off as well, causing an increase in heat rate of the machine. Someoperators are faced with this situation every day and as a result, asthe load demand falls, gas turbine plants hit its lower operating limitand the gas turbines have to be turned off, which causes the power plantto incur a tremendous maintenance cost penalty.

Another characteristic of a typical gas turbine is that as the ambienttemperature increases, the power output goes down proportionately due tothe linear effect of the reduced density as the temperature of airincreases. Power output can be down by more than 10% from nameplatepower rating during hot days, which is typically when peaking gasturbines are called on most frequently to deliver power.

Another characteristic of typical gas turbines is that air that iscompressed and heated in the compressor section of the gas turbine isducted to different portions of the gas turbine's turbine section whereit is used to cool various components. This air is typically calledturbine cooling and leakage air (hereinafter “TCLA”) a term that is wellknown in the art with respect to gas turbines. Although heated from thecompression process, TCLA air is still significantly cooler than theturbine temperatures, and thus is effective in cooling those componentsin the turbine downstream of the compressor. Typically 10% to 15% of theair that enters the inlet of the compressor bypasses the combustor andis used for this process. Thus, TCLA is a significant penalty to theperformance of the gas turbine system.

Other power augmentation systems, like inlet chilling for example,provide cooler inlet conditions, resulting in increased air flow throughthe gas turbine compressor, and the gas turbine output increasesproportionately. For example, if inlet chilling reduces the inletconditions on a hot day such that the gas turbine compressor has 5% moreair flow, the output of the gas turbine will also increase by 5%. Asambient temperatures drops, inlet chilling becomes less effective, sincethe air is already cold. Therefore, inlet chilling power increase ismaximized on hot days, and tapers off to zero at approximately 45° F.ambient temperature days.

In power augmentation systems such as the one discussed in U.S. Pat. No.6,305,158 to Nakhamkin (the “'158 patent”), there are three basic modesof operation defined, a normal mode, charging mode, and an air injectionmode, but it is limited by the need for an electrical generator that hasthe capacity to deliver power “exceeding the full rated power” that thegas turbine system can deliver. The fact that this patent has beenissued for more than ten (10) years and yet there are no knownapplications of it at a time of rapidly rising energy costs is proofthat it does not address the market requirements.

First of all, it is very expensive to replace and upgrade the electricalgenerator so it can deliver power “exceeding the full rated power” thatthe gas turbine system can currently deliver. Also, although theinjection option as disclosed in the '158 patent provides poweraugmentation, it takes a significant amount of time to start and get online to the electrical grid. This makes application of the '158 patentimpractical in certain markets like spinning reserve, where the powerincrease must occur in a matter of seconds, and due to do the need forthe large auxiliary compressor in these types of systems, that takes toolong to start.

Another drawback is that the system cannot be implemented on a combinedcycle plant without significant negative impact on fuel consumption andtherefore efficiency. Most of the implementations outlined in the '158patent use a recuperator to heat the air in simple cycle operation,which mitigates the fuel consumption increase issue, however, it addssignificant cost and complexity. The proposed invention outlined belowaddresses both the cost and performance shortfalls of the inventiondisclosed in the '158 patent.

Also, as outlined in a related U.S. Pat. No. 5,934,063 to Nakhamkin (the“'063 patent”), there is a valve structure that “selectively permits oneof the following modes of operation: there is a gas turbine normaloperation mode, a mode where air is delivered from the storage systemand mixed with air in the gas turbine, and then a charging mode”. The'063 patent has also been issued for more than ten (10) years and thereare also no known applications of it anywhere in the world. The reasonfor this is again cost and performance shortfalls, similar to thoserelated to the '158 patent. Although this system can be applied withoutan efficiency penalty on a simple cycle gas turbine, simple cycle gasturbines do not run very often so they typically do not pay off thecapital investment in a timeframe that makes the technology attractiveto power plant operators. Likewise, if this system is applied to acombined cycle gas turbine, there is a significant heat rate penalty,and again the technology does not address the market needs. The proposedinvention outlined below addresses both the cost and performance issuesof the '063 patent.

SUMMARY OF THE INVENTION

The current invention, which may be referred to herein as TurboPHASE™,provides several options, depending on specific plant needs, to improvethe efficiency and power output of a plant at low loads, and to reducethe lower limit of power output capability of a gas turbine while at thesame time increasing the upper limit of the power output of the gasturbine, thus increasing the capacity and regulation capability of a newor existing gas turbine system.

One aspect of the present invention relates to methods and systems thatallow running gas turbine systems to provide additional power quicklyduring periods of peak demand.

Another aspect of the present invention relates to an energy storage andretrieval system for obtaining useful work from an existing source of agas turbine power plant.

Yet another aspect of the present invention relates to methods andsystems that allow gas turbine systems to be more efficiently turneddown during periods of lowered demand.

One embodiment of the invention relates to a system comprising at leastone existing gas turbine that comprises one first compressor, at leastone electrical generator, at least one turbine connected to thegenerator and the compressor, a combustor, and a combustion case (whichis the discharge manifold for the compressor) and further comprising asupplemental compressor which is not the same as the first compressor.

An advantage of other preferred embodiments of the present invention isthe ability to increase the turn down capability of the gas turbinesystem during periods of lower demand and improve the efficiency andoutput of the gas turbine system during periods of high demand.

Another advantage of embodiments of the present invention is the abilityto increase the turn down capability of the gas turbine system duringperiods of low demand by using a supplemental compressor driven by afueled engine, operation of which is which is independent of theelectric grid.

Another advantage of embodiments of the present invention is the abilityto increase the turn down capability of the gas turbine system duringperiods of low demand by using a supplemental compressor driven by afueled engine which produces heat that can be added to compressed airflowing to the combustion case, from either the supplemental compressor,an air storage system, or both, or such heat can be added to the steamcycle in a combined cycle power plant.

Another advantage of some embodiments of the present invention is theability to increase output of the gas turbine system during periods ofhigh demand by using a supplemental compressor which is not driven bypower produced by the gas turbine system.

Another advantage of some embodiments of the present invention is theability to increase output of the gas turbine system during periods ofhigh demand by using a supplemental compressor which is driven by steamproduced by the heat recovery steam generator of a combined cycle powerplant.

Another advantage of the present invention is the ability to incorporateselective portions of the embodiments on existing gas turbines toachieve specific plant objectives.

Another advantage of an embodiment of the present invention is theability to inject compressed air into a turbine cooling circuit withoutheating up the air prior to such injection, and because cool cooling aircan achieve the same desired metal temperatures with use of lesscompressed air (as compared to heated compressed air), efficiency isimproved.

Another advantage of another embodiment of the present invention is thatbecause the incremental amount of compressed air can be added at arelatively constant rate over a wide range of ambient temperatures, thepower increase achieved by the gas turbine is also relatively constantover a wide range of ambient temperatures. Additionally, since thesupplemental compressed air is delivered without any significant powerincrease from the gas turbine's compressor, (because the compressed airis from either a separately fueled compressor or an a compressed airstorage system), for every 1% of air injected (by mass flow), a 2% powerincrease results. This is significant because other technologies, suchas inlet chillers, for supplementing power yield closer to a 1% powerincrease for each 1% increase of injected air, therefore, twice as muchpower boost is achieved with the same incremental air flow through theturbine and combustor, resulting in a physically smaller, and lowercost, power supplementing system.

One preferred embodiment of the present invention includes anintercooled compression circuit using a supplemental compressor toproduce compressed air that is stored in one or more high pressure airstorage tanks, wherein the intercooling process heat absorbed from thecompressed air during compression is transferred to the steam cycle of acombined cycle power plant.

Optionally, when integrated with a combined cycle gas turbine plant witha steam cycle, steam from the steam cycle can be used to drive asecondary steam turbine which in turn drives a supplemental compressor.The use of high pressure air storage tanks in conjunction with firingthis air directly in the gas turbine gives the gas turbine the abilityto deliver much more power than could be otherwise produced, because themaximum mass flow of air that is currently delivered by the gas turbinesystem's compressor to the turbine is supplemented with the air from theair tanks. On existing gas turbines, this can increase the output of agas turbine system up to the current generator limit on a hot day, whichcould be as much as an additional 20% power output, while at the sametime increasing the turn down capability by 25-30% more than currentstate of the art.

On new gas turbines, the generator and turbine can be oversized todeliver this additional power at any time, thus increasing the nameplate power rating of the system by 20% at a total system cost increasethat is much lower than 20%, with 25-30% more turn down capability thanthe current state of the art.

Other advantages, features and characteristics of the present invention,as well as the methods of operation and the functions of the relatedelements of the structure and the combination of parts will become moreapparent upon consideration of the following detailed description andappended claims with reference to the accompanying drawings, all ofwhich form a part of this specification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of an embodiment of the present inventionhaving a supplemental energy system with a recuperated engine drivingthe supplemental compressor.

FIG. 2 is a schematic drawing of an embodiment of the present inventionhaving a supplemental energy system with a recuperated engine drivingthe supplemental compressor and energy storage.

FIG. 3 is a schematic drawing of an embodiment of the present inventionincorporating a continuous power augmentation system.

FIG. 4 is a schematic drawing of an embodiment of the present inventionin which an auxiliary steam turbine is drives the supplementalcompressor.

FIG. 5 is a schematic drawing of an embodiment of the present inventionin which includes an auxiliary steam turbine driving the supplementalcompressor and energy storage.

FIG. 6 is a schematic drawing of an embodiment of the present inventioninstalled in conjunction with two gas turbines and a steam turbine.

FIG. 7 is a schematic drawing of an embodiment of the present inventioninstalled in conjunction with one gas turbine and a steam turbine.

FIG. 8 is a schematic drawing of an embodiment of the present inventioninstalled in conjunction with one gas turbine.

DETAILED DESCRIPTION OF THE INVENTION

The components of one embodiment of the present invention are shown inFIG. 1 as they are used with an existing gas turbine system 1. Theexisting gas turbine system 1, which compresses ambient air 2, includesa compressor 10, combustor 12, combustion case 14, turbine 16 andgenerator 18. A fueled engine 20 is used to drive a multistageintercooled supplemental compressor 22 which compresses ambient air 24and discharges compressed air 26. As used herein, the term “fueledengine” means a reciprocating internal combustion engine, a gas turbine(in addition to the gas turbine in the existing gas turbine system 1, ora similar machine that converts fuel into energy through an exothermicreaction such as combustion (e.g., gasoline, diesel, natural gas, orbiofuel and similar fuel). The fueled engine draws in ambient air 42 andas a result of the combustion process, produces hot exhaust gas 32. Asthose skilled in the art will readily appreciate, as air in thesupplemental compressor 22 passes from one compressor stage to the next,the air is intercooled by use of an intercooler heat exchanger 28, suchas a cooling tower, to reduce the work required to compress the air atthe subsequent compressor stage. As used herein, the term “intercoolerheat exchanger” means a heat exchanger that receives compressed air froman upstream stage of a compressor, and cools that air before deliveringit to another compression stage downstream of the upstream compressorstage. Use of the intercooler heat exchanger 28 increases the efficiencyof the supplemental compressor 22, which makes it more efficient thanthe compressor 10 of the existing gas turbine system 1. As those skilledin the art will readily appreciate, although referred to herein as an“intercooler”, the intercooler heat exchanger 28 actually includes anintercooler and an after-cooler as described in greater detail below.

This embodiment further includes a recuperator 30, which is a heatexchanger that receives the exhaust gas 32 from the fueled engine 20 andthe compressed air 26 from the supplemental compressor 22. Flow ofcompressed air from the supplemental compressor 22 to the recuperator 30is controlled by the recuperator flow control valve 44. Within therecuperator 30, the hot exhaust gas 32 heats the compressed air 26 andthen exits the recuperator 30 as substantially cooler exhaust gas 34. Atthe same time in the recuperator 30, the compressed air 26 absorbs heatfrom the exhaust gas 32 and then exits the recuperator 30 assubstantially hotter compressed air 36 than when it entered therecuperator 30. The substantially hotter compressed air 36 is thendischarged from the recuperator 30 into the combustion case 14 of thegas turbine system 1 where it becomes an addition to the mass flowthrough the turbine 16.

The cooler exhaust gas 34 is then discharged to atmosphere. A selectivecatalytic reduction (“SCR”) device (not shown) of the type known in theart, can be inserted before, in the middle of, or after the recuperator30 to achieve the most desirable condition for the SCR function.Alternately, after the SCR device, the cooler exhaust gas 34 can beinjected into the exhaust gas 38 of the turbine 16 as shown in FIG. 1,and then the mixed flow exhaust 38 will either be discharged to theatmosphere (in the case for the simple cycle gas turbine) or directed tothe heat recovery steam generator (“HRSG”) of a steam turbine of thetype known in the art (not shown) in combined cycle power plants. If themixed flow exhaust 38 is to be discharged into the HRSG, the means usedmust ensure that the exhaust gas 38 flow from the turbine 16 into theHRSG and the SCR device is not disrupted. On “F-Class” engines, such asthe General Electric Frame 9FA industrial gas turbine, there are largecompressor bleed lines that, for starting purposes, bypass air aroundthe turbine section and dump air into the exhaust plenum of the turbine16. These bleed lines are not in use when the gas turbine system 1 isloaded, and therefore are a good place to discharge the cooler exhaustgas 34 after it exits the recuperator 30, since these compressor bleedlines are already designed to minimize the impact on the HRSG and SCRdevice. By injecting the exhaust 32 from the fueled engine 20 into toexhaust 38 of the gas turbine system 1, the SCR of the gas turbinesystem 1 may be used to clean the exhaust 32, thus eliminating anexpensive system on the fueled engine 20.

It turns out that gasoline, diesel, natural gas, or biofuel and similarreciprocating engines are not sensitive to back pressure, so putting therecuperator 30, on the fueled engine 20 does not cause a measurableeffect on the performance of the fueled engine 20. This is significantbecause other heat recovery systems, such as the HRSGs used in theexhaust of a typical gas turbine power plants, create a significantpower loss all of the time, independent of whether a power augmentationsystem is in use or not.

The power from the fueled engine 20 is used to drive the intercooledcompressor 22. If the installation does include a HSRG and a steamturbine, the auxiliary heat from the engine jacket, oil cooler andturbocharger on the fueled engine 20 can be transferred into the steamcycle of the steam turbine via the HSRG (typically the low pressure andtemperature condensate line). Likewise, heat removed by the intercoolerheat exchanger 28 from the air as it is compressed in the multistagesupplemental compressor 22 can be transferred into the steam cycle in asimilar manner, prior to the compressed air being cooled by the coolingtower, to lower the temperature of the compressed air to the desiredtemperature prior to entering the subsequent compression stage of thesupplemental compressor 22. If an auxiliary gas turbine is used as thefueled engine 20 instead of a reciprocating engine, lower emission rateswill be achievable, which will allow emission permitting even in thestrictest environmental areas. Also, if the auxiliary gas turbine isused as the fueled engine 20, the exhaust gas from the auxiliary gasturbine can be piped directly to the exhaust bleed pipes of the existinggas turbine system 1 described above, thus avoiding the cost andmaintenance of an additional SCR device.

When peaking with this system, the gas turbine system 1 will most likelybe down in power output and flow (assuming that the peaking is needed inthe summer when higher ambient air temperatures reduce total mass flowthrough the gas turbine system 1 which in turn reduces power output ofthe gas turbine system 1 as a whole, and the supplemental compressor 22will just bring the air mass flow through the gas turbine system 1 backup to where the flow would have been on a cooler day (i.e. a day onwhich the full rated power of the gas turbine system 1 could beachieved).

FIG. 2 shows the embodiment of FIG. 1 with the addition of compressedair storage. The compressed air storage system includes an air storagetank 50, a hydraulic fluid tank 52, and a pump 54 for transferringhydraulic fluid, such as water, between the hydraulic fluid tank 52 andthe air storage tank 50. According to preferred embodiments, duringperiods when increased power delivery is needed, the air exit valve 46opens, the air bypass valve 48 opens, the air inlet valve 56 closes, andthe supplemental compressor 22 is operated, driven by the fueled engine20. As one skilled in the art will readily appreciate, if compressed airis to be stored for later use, it will likely need to be stored at ahigher pressure, thus, the supplemental compressor 22 would preferablyhave additional stages of compression, as compared to the supplementalcompressor 22 of the embodiment shown in FIG. 1. These additional stagesmay be driven by the fueled engine 20 all the time, or may be capable ofbeing driven intermittently by installing a clutch type mechanism thatonly engages the additional stages when the fueled engine 20 is operatedto store compressed air in the air storage tank 50 (where the desiredstorage pressure is substantially higher to minimize the required volumeof the air storage tank 50). Alternatively, the additional stages may bedecoupled from the fueled engine 20 and driven by a separately fueledengine (not shown) or other means, such as an electric motor.

The compressed air 26 flowing from the supplemental compressor 22 isforced to flow to the mixer 58 as opposed to towards the intercoolerheat exchanger 28 because the air inlet valve 56, which controls airflow exiting the intercooler heat exchanger 28, is closed. Thecompressed air 26 flowing from the outlet of the supplemental compressor22 is mixed in the mixer 58 with the compressed air exiting the airstorage tank 50 and introduced to the recuperator 30 where it absorbsheat from the exhaust gas of the fueled engine 20 before beingintroduced into the combustion case 14 using the process describedbelow. As those skilled in the art will readily appreciate, for thermalefficiency purposes, the recuperator 30 would ideally be a counter-flowheat exchanger, since that would allow the maximum amount of heat fromthe exhaust 32 to be transferred to the compressed air exiting the airstorage tank 50. Alternately, if the recuperator 30 is made up of one ormore cross-flow heat exchangers, it can have a first stage, which is afirst cross-flow heat exchanger, followed by a second stage, which is asecond cross-flow heat exchanger. In this configuration, where theexhaust 32 first enters the first stage of the recuperator, is partiallycooled, then flows to the second stage of the recuperator. At the sametime, the compressed air exiting the air storage tank 50 first entersthe second stage of the recuperator 30, where additional heat isextracted from the partially cooled exhaust 32, thereby “pre-heating”the compressed air. The compressed air then flows to the first stage ofthe recuperator 30 where it is heated by exhaust 32 that has not yetbeen partially cooled, prior to flowing to the mixer 58 to join the airflowing from the supplemental compressor 22. In this case, the “twostage” recuperator acts more like a counter-flow heat exchanger,yielding higher thermal efficiency in the heating of the compressed air.

As those skilled in the art will readily appreciate, since the air beingcompressed in the supplemental compressor 22 is bypassing theintercooler heat exchanger 28 due to the bypass valve 48 being open, thecompressed air exiting the supplemental compressor 22 retains some ofthe heat of compression, and when mixed with the compressed air flowingfrom the air storage tank 50, will increase the temperature of the mixedair so that when the mixed air enters the recuperator 30, it is hotterthan it would be if only compressed air from the air storage tank 50 wasbeing fed into the recuperator 30. Likewise, if the air exiting the airstorage tank 50 is first preheated in a “second stage” of therecuperator as described above prior to entering the mixer 58, an evenhotter mixture of compressed air will result, which may be desirableunder some conditions.

As the combustion turbine system 1 continues to be operated in thismanner, the pressure of the compressed air in the air storage tank 50decreases. If the pressure of the compressed air in the air storage tank50 reaches the pressure of the air in the combustion case 14, compressedair will stop flowing from the air storage tank 50 into the gas turbinesystem 1. To prevent this from happening, as the pressure of thecompressed air in the air storage tank 50 approaches the pressure of theair in the combustion case 14, the fluid control valve 60 remainsclosed, and the hydraulic pump 54 begins pumping a fluid, such as water,from the hydraulic fluid tank 52 into the air storage tank 50 at apressure high enough to drive the compressed air therein out of the airstorage tank 50, thus allowing essentially all of the compressed air inthe air storage tank to be delivered to the combustion case 14.

As those skilled in the art will readily appreciate, if additionalcompressor stages, or high pressure compressor stages, are addedseparate from the supplemental compressor 22 driven by the fueled engine20, then, if desired, air from the gas turbine combustion case 14 can bebled and allowed to flow in reverse of the substantially hottercompressed air 36 as bleed air from the gas turbine combustion case 14and take the place of air from the separately fueled engine 20 drivensupplemental compressor 22. In this case, the bleed air could be cooledin the intercooler heat exchanger 28, or a cooling tower, and thendelivered to the inlet of the high pressure stages of the supplementalcompressor 22. This may be especially desirable if low turn downcapability is desired, as the bleed air results in additional gasturbine power loss, and the drive system for the high pressure stages ofthe supplemental compressor 22 can driven by an electric motor,consuming electrical power generated by the gas turbine system 1, whichalso results in additional gas turbine power loss. As those skilled inthe art will readily appreciate, this is not an operating mode thatwould be desirable during periods when supplemental power productionfrom the gas turbine system is desired.

According to preferred embodiments, independent of whether or not thehydraulic system is used, when the air stops flowing from the airstorage tank 50, the supplemental compressor 22 can continue to run anddeliver power augmentation to the gas turbine system 1. According toother preferred embodiments, such as the one shown in FIG. 1, thesupplemental compressor 22 is started and run without use of an airstorage tank 50. Preferably, an intercooler heat exchanger 28 is used tocool air from a low pressure stage to a high pressure stage in thesupplemental compressor 22 that compresses ambient air 24 through amultistage compressor 22.

The air inlet valve 56, the air outlet valve 46, the bypass valve 48,and the supplemental flow control valve 44, are operated to obtain thedesired operating conditions of the gas turbine system 1. For example,if it is desired to charge the air storage tank 50 with compressed air,the air outlet valve 46, the bypass valve 48 and the supplemental flowcontrol valve 44 are closed, the air inlet valve 56 is opened and thefueled engine 20 is used to drive the supplemental compressor 22. As airis compressed in the supplemental compressor 22, it is cooled by theintercooler heat exchanger 28 because the bypass valve 48 is closed,forcing the compressed air to flow through the intercooler heatexchanger 28. Air exiting the supplemental compressor 22 then flowsthrough the air inlet valve 56 and into the air storage tank 50.Likewise, if it is desired to discharge compressed air from the airstorage tank 50 and into the combustion case 14 the air outlet valve 46,the bypass valve 48 and the supplemental flow control valve 44 areopened, and the air inlet valve 56 can be closed, and the fueled engine20 can be used to drive the supplemental compressor 22. As air iscompressed in the supplemental compressor 22, it heats up due to theheat of compression, and it is not cooled in the intercooler heatexchanger because bypass valve 48 is open, thereby bypassing theintercooler heat exchanger. Compressed air from the air storage tank 50then flows through the mixer 58 where it is mixed with hot air from thesupplemental compressor 22 and then flows to the recuperator 30 where itabsorbs heat transferred to the recuperator 30 from the exhaust gas 32of the fueled engine 20 and then flows on to the combustion case 14. Inthe event that all of the airflow from the supplemental compressor 22 isnot needed by the gas turbine system 1, this embodiment can be operatedin a hybrid mode where the some of the air flowing from the supplementalcompressor 22 flows to the mixer 58 and some of the air flow from thesupplemental compressor 22 flows through the intercooler heat exchanger28 and then through the air inlet valve 56 and into the air storage tank50.

As those skilled in the art will readily appreciate, the preheated airmixture could be introduced into the combustion turbine at otherlocations, depending on the desired goal. For example, the preheated airmixture could be introduced into the turbine 16 to cool componentstherein, thereby reducing or eliminating the need to extract bleed airfrom the compressor to cool these components. Of course, if this werethe intended use of the preheated air mixture, the mixture's desiredtemperature would be lower, and the mixture ratio in the mixer 58 wouldneed to be changed accordingly, with consideration as to how much heat,if any, is to be added to the preheated air mixture by the recuperator30 prior to introducing the compressed air mixture into the coolingcircuit(s) of the turbine 16. Note that for this intended use, thepreheated air mixture could be introduced into the turbine 16 at thesame temperature at which the cooling air from the compressor 10 istypically introduced into the TCLA system of the turbine 16, or at acooler temperature to enhance overall combustion turbine efficiency(since less TCLA cooling air would be required to cool the turbinecomponents).

It is to be understood that when the air storage tank 50 has hydraulicfluid in it prior to the beginning of a charging cycle to add compressedair to the air storage tank 50, the fluid control valve 60 is opened sothat as compressed air flows into the air storage tank 50 it drives thehydraulic fluid therein out of the air storage tank 50, through thefluid control valve 60, and back into the hydraulic fluid tank 52. Bycontrolling the pressure and temperature of the air entering the turbinesystem 1, the gas turbine system's turbine 16 can be operated atincreased power because the mass flow of the gas turbine system 1 iseffectively increased, which among other things, allows for increasedfuel flow into the gas turbine's combustor 12. This increase in fuelflow is similar to the increase in fuel flow associated with cold dayoperation of the gas turbine system 1 where an increased mass flowthrough the entire gas turbine system 1 occurs because the ambient airdensity is greater than it is on a warmer (normal) day.

During periods of higher energy demand, the air flowing from the airstorage tank 50 and supplemental compressor 22 may be introduced to thegas turbine system 1 in a manner that offsets the need to bleed coolingair from the compressor 10, thereby allowing more of the air compressedin the compressor 10 to flow through the combustor 12 and on to theturbine 16, thereby increasing the net available power of the gasturbine system 1. The output of the gas turbine 16 is very proportionalto the mass flow rate through the gas turbine system 1, and the systemdescribed above, as compared to the prior art patents, delivers higherflow rate augmentation to the gas turbine 16 with the same air storagevolume and the same supplemental compressor size, when the two are usedsimultaneously to provide compressed air, resulting in a hybrid systemthat costs much less than the price of prior art systems, whileproviding comparable levels of power augmentation.

The supplemental compressor 22 increases the pressure of the ambient air24 through at least one stage of compression, which is then cooled inthe intercooler heat exchanger 28, further compressed in a subsequentstage of the supplemental compressor 22, and then after-cooled in theintercooler heat exchanger 28 (where the compressed air exiting the laststage of the supplemental compressor 22 is then after-cooled in the sameintercooler heat exchanger 28), and then the cooled, compressed, highpressure air is delivered to the air storage tank 50 via the open airinlet valve 56 and the inlet manifold 62, and is stored in the airstorage tank 50.

As the pressurized air flowing through the intercooler heat exchanger 28is cooled, the heat transferred therefrom can be used to heat water inthe HRSG to improve the efficiency of the steam turbine. An alternatemethod to cool the compressed air in the intercooler heat exchanger 28is to use relatively cool water from the steam cycle (not shown) on acombined cycle plant. In this configuration, the water would flow intothe intercooler heat exchanger 28 and pick up the heat that is extractedfrom the compressed air from the supplemental compressor 22, and thethen warmer water would exit the intercooler heat exchanger 28 and flowback to the steam cycle. With this configuration, heat is capturedduring both the storage cycle described in this paragraph, and the poweraugmentation cycle described below.

According to preferred embodiments, the air storage tank 50 isabove-ground, preferably on a barge, skid, trailer or other mobileplatform and is adapted or configured to be easily installed andtransported. The additional components, excluding the gas turbine system1, should add less than 20,000 square feet, preferably less than 15,000square feet, and most preferably less than 10,000 square feet to theoverall footprint of the power plant. A continuous augmentation systemof the present invention takes up 1% of the footprint of a combinedcycle plant and delivers from three to five times the power per squarefoot as compared to the rest of the plant, thus it is very spaceefficient, while a continuous augmentation system of the presentinvention with storage system takes up 5% of the footprint of thecombined cycle plant and delivers from one to two times the power persquare foot of the power plant.

FIG. 3 shows another embodiment of the present invention in which anauxiliary gas turbine 64 is used to provide supplemental air flow attimes when additional power output from the gas turbine system 1 isneeded. The auxiliary gas turbine 64 includes a supplemental compressorsection 66 and a supplemental turbine section 68. In this embodiment,the auxiliary gas turbine is designed so that substantially all of thepower produced by the supplemental turbine section 68 is used to drivethe supplemental compressor section 66. As used herein the term“substantially all” means that more than 90% of the power produced bythe supplemental turbine section 68 is used to drive the supplementalcompressor 66, because major accessories, such as the electric generatorused with the gas turbine system 1, are not drawing power from theauxiliary gas turbine section 68. Manufacturers of small gas turbines,such as Solar Turbines Inc., have the capability to mix and matchcompressors and combustors/turbines because they build their systemswith multiple bearings to support the supplemental compressor section 66and the supplemental turbine section 68. A specialized turbine, with anoversized gas turbine compressor 66 and with a regular sizedturbine/combustion system 68 is used to provide additional supplementalairflow to the gas turbine system 1, and the excess compressed air 70output from the oversized compressor 66, which is in excess of what isneeded to run the turbine/combustion system 68, flows through thecombustion case flow control valve 74, when it is in the open position,and is discharged into the combustion case 14 of the gas turbine system1 to increase the total mass flow through the turbine 16 of the gasturbine system 1, and therefore increases the total power output by thegas turbine system 1. For example, a 50 lb/sec combustor/turbine section68 that would normally be rated for 4 MW, may actually be generating 8MW, but the compressor is drawing 4 MW, so the net output from thegenerator is 4 MW. If such a turbine were coupled with a 100 lb/seccompressor on it, but only 50 lbs/sec were fed to the combustor/turbinesection 68, the other 50 lb/sec could be fed to the combustion case ofthe gas turbine system 1. The exhaust 72 of the 50 lb/seccombustor/turbine section 68 could be injected into the exhaust 38 ofthe main turbine 16 similar to the manner described in the embodimentshown in FIG. 1, and jointly sent to the SCR. Optionally, the exhaustcan be separately treated, if required.

Obviously, the pressure from the 100 lb/sec compressor 66 has to besufficient to drive the compressed air output therefrom into thecombustion case 14. Fortunately, many of the smaller gas turbine enginesare based on derivatives of aircraft engines and have much higherpressure ratios than the large industrial gas turbines used at mostpower plants. As shown in FIG. 3, this embodiment of the presentinvention does not include the recuperator 30, the intercooledcompressor 22, or the intercooler heat exchanger 28 shown in FIGS. 1 and2. Of course, the embodiment shown in FIG. 3 does not provide theefficiency improvement of the intercooled embodiments shown in FIGS. 1and 2, however the initial cost of the embodiment shown in FIG. 3 issubstantially less, which may make it an attractive option to operatorsof power plants that typically provide power in times of peak demand,and that therefore are not run much and are less sensitive to fuelefficiency. When the auxiliary gas turbine 64 is not running, thecombustion case flow control valve 74 is closed.

The embodiment shown in FIG. 4 shows another way to incorporate asupplemental compressor 22 into the gas turbine system 1. In somesituations, the gas turbine augmentation of the present invention with(i) the additional mass flow to the HRSG, and/or (ii) the additionalheat from the intercooler heat exchanger 28 and fueled engine 20 (ascompared to a gas turbine system 1 that does not incorporate the presentinvention), may be too much for the steam turbine and/or the steamturbine generator to handle if all of the additional heat flows to thesteam turbine generator (especially if the power plant has duct burnersto replace the missing exhaust energy on hot days). In this case, theadditional steam generated as a result of adding the heat of compressiongenerated by the supplemental compressor 22 can be extracted from thesteam cycle HRSG. As it happens, when compressed air augmentation isadded to the gas turbine system 1, the heat energy extracted from theintercooler heat exchanger 28 generates about the same amount of energythat it takes to drive the supplemental compressor 22. In other words,if you had a steam turbine that generated 100 MW normally and 108 MWwhen the supplemental compressor 22 was injecting compressed air intothe gas turbine system 1, the extra 8 MW is approximately equal to thepower requirement to drive the intercooled supplemental compressor 22.Therefore, if some of the steam is extracted from the steam cycle of thepower plant, and the steam turbine is kept at 100 MW, a small auxiliarysteam turbine 76 can be used to drive the intercooled supplementalcompressor 22, and there would be no additional source of emissions atthe power plant.

In FIG. 4, an auxiliary steam turbine 76 drives the intercooledsupplemental compressor 22 and the steam 78 that is used to drive thesteam engine 76, which comes from the HRSG (not shown) of the powerplant, is the extra steam produced from the heat, being added to theHRSG, which was extracted by the intercooler heat exchanger 22 duringcompression of air in the supplemental compressor 22. The exhaust 80 ofthe steam engine 76 is returned to the HRSG where it is used to producemore steam. This embodiment of the present invention results in asignificant efficiency improvement because the compression process ofthe supplemental compressor 22 is much more efficient than thecompressor 10 of the gas turbine system 1. In this situation, the poweraugmentation level will, of course, be reduced as the steam turbine willnot be putting out additional MW, however there will be no other sourceof emissions/fuel burn.

FIG. 5 shows the embodiment of FIG. 4 with the addition of compressedair storage. This implementation of compressed air energy storage issimilar to that described with respect to FIG. 2, as is the operationthereof. As those skilled in the art will readily appreciate, the poweraugmentation level of the embodiment shown in FIG. 5 is less than theembodiment shown in FIG. 2, since the steam turbine will not be puttingout additional MW, however there will be no other source ofemissions/fuel burn.

FIGS. 6-8 show various implementations of the embodiment shown in FIG.1, referred to as the “TurboPHASE system”. TurboPHASE, which is asupplemental power system for gas turbine systems, is a modular,packaged “turbocharger” that can be added to most, if not all, gasturbines, and can add up to 20% more output to existing simple cycle andcombined cycle plants, while improving efficiency (i.e. “heat rate”) byup to 7%. The TurboPHASE system is compatible with all types of inletchilling or fogging systems, and when properly implemented, will leaveemissions rates (e.g. ppm of NOx, CO, etc.) unchanged, while thespecific emissions rates should improve as the result of improvement inheat rate. Since only clean air, at the appropriate temperature, isinjected into the turbine, the TurboPHASE system has no negative effecton gas turbine maintenance requirements. Due to the factory-assembled &tested modules that make up the TurboPHASE system, installation at anexisting power plant is quick, requiring only a few days of the gasturbine system being down for outage to complete connections and toperform commissioning.

FIG. 6 shows an implementation of the embodiment of the presentinvention shown in FIG. 1 in conjunction with two 135 MW GeneralElectric Frame 9E industrial gas turbines 82, 84 in a combined cycleconfiguration with a 135 MW steam turbine 86 (“ST”). The results of thisimplementation are shown below in Table 1.

TABLE 1 (7.0% additional Flow added to 2 × 1 9E combined cycle on a 59F. day (+71 lbs/sec per GT)) Existing plant With TurboPHASE ™ CompressorPressure ratio 12.7 13.6 Compressor discharge temperature 673 F. 760 .FCompressor discharge pressure 185 psi 197 psi Turbine Firing temperature2035 F. 2035 F. Turbine exhaust temperature 1000 F. 981 F. (−19 F.) 9EGT Output (MW each) 135 MW (base load each) +23 MW (+17% output)Increase flow N/A +20.7 Increase PR turbine output (delta) N/A +5.6Increase PR compressor load (delta) N/A −3.3 ST output (MW) 135 MW (baseload) +16 MW (+12%) Increased flow N/A +9.4 Cooler Exhaust temp N/A −2.9Jacket heat and IC heat put into ST N/A +9.9 9E Plant Output SC (MW) 135MW (base load) 158 MW (+23 MW or +17%) 9E Plant Output CC (MW) 405 MW(base load) 467 MW (+62 MW or +15%) Base load Fuel Burn per GT 1397MMBTU/hr 1514 MMBTU/hr Fuel burn of aux engine delivering 71 lbs/sec N/A96 MMBTU/hr (740 Gal/hr ~15.000HP) Total additional fuel burn of GT N/A11 MMBTU/hr (+1%) Increase flow N/A 98 MMBTU/hr (+7%) IncreasedRR/higher CDT/mixed temp N/A −77 MMBTU/hr Total Plant Fuel Burn CC 2974MMBTU/hr 3028 MMBTU/hr Heat rate SC 10350 BTU/kWh 5582 BTU/kWh (−767BTU/kWh or −7%) Heat rate CC 6900 BTU/kWh 6483 BTU/kWh (−416 BTU/kWh or−6%)

As is clear from Table 1, the implementation increased power output fromeach of the gas turbines by 23 MW, and increased power output from thesteam turbine by 6 MW, for a total of 52 MW (2×23 MW+6 MW=52 MW). TheTurboPHASE system increases air flow to the gas turbines by 7%, isoperable at any ambient temperature, and yields a 4% heat rateimprovement. In doing so, the pressure ratio (“PR”) at the gas turbineoutlet of each gas turbine increased by 5.6, while the PR of thecompressor load exhibited a 3.3 decrease. The total fuel consumptionrate for the combined cycle (“CC”) plant increased by 54 MMBTU/hr whilethe heat rate for the CC plant decreased by 416 BTU/kWh. Forinformational purposes, Table 1 also shows that if the implementationhad been on a simple cycle (“SC”) plant, the increased power output fromeach of the gas turbines by would have totaled 46 MW, while the heatrate would have decreased by 767 BTU/kWh. As an option, the intercoolerheat exchanger can be eliminated and the supplemental compressor heatand engine heat added to the steam turbine cycle, which increases SToutput from +6 MW to +16 MW (62 MW total) and improves heat rate by 6%.

FIG. 7 shows an implementation of the embodiment shown in FIG. 1 on a CCplant comprising one General Electric Frame 9FA industrial gas turbine82 and one 138 MW steam turbine. In this implementation, power output bythe 9FA industrial gas turbine 82 is increased by 42 MW from 260 MW, andpower output by the steam turbine 88 is increased by 8 MW, for a totalpower output increase of 50 MW, along with a heat rate improvement of0.25%. As an option, the intercooler heat exchanger 28 can be eliminatedand the heat of compression of the supplemental compressor 22 and theheat from the exhaust 32 of the fueled engine can be added to the HRSGin the steam cycle, which increases ST output from +8 MW to +14 MW (56MW total) and improves heat rate to 1.8%.

FIG. 8 shows an implementation of the embodiment shown in FIG. 1 on a SCplant comprising one General Electric Frame 9B (or 9E) industrial gasturbine 90. In this implementation, power output by the 9B is increasedby 23 MW from 135 MW, along with a heat rate improvement of 7%.

Implementation of the embodiments of the present invention preferablyprovide the following benefits:

-   -   (i) Installation is quick and simple, with no major electric        tie-in required.    -   (ii) No change in gas turbine firing temperature, so gas turbine        maintenance costs are unchanged.    -   (iii) It uses existing ports on gas turbine system's combustion        case to inject air.    -   (iv) High efficiency, recuperated and internal combustion        engine-driven inter-cooled supplemental compressor improves both        SC and CC heat rates.    -   (v) It is compatible with water injection, fogging, inlet        chilling, steam injection, and duct burners.    -   (vi) Air is injected into gas turbine combustion case at        compatible temperatures and pressures.    -   (vii) The internal combustion, reciprocating, fueled engine can        burn natural gas, low BTU biofuel or diesel (also available with        small steam turbine driver and small gas turbine driver for the        fueled engine.)    -   (viii) Energy storage option also available: approximately 2        times the price and 2 times the efficiency improvement.

While the particular systems, components, methods, and devices describedherein and described in detail are fully capable of attaining theabove-described objects and advantages of the invention, it is to beunderstood that these are the presently preferred embodiments of theinvention and are thus representative of the subject matter which isbroadly contemplated by the present invention, that the scope of thepresent invention fully encompasses other embodiments which may becomeobvious to those skilled in the art, and that the scope of the presentinvention is accordingly to be limited by nothing other than theappended claims, in which reference to an element in the singular means“one or more” and not “one and only one”, unless otherwise so recited inthe claim. It will be appreciated that modifications and variations ofthe invention are covered by the above teachings and within the purviewof the appended claims without departing from the spirit and intendedscope of the invention.

1. A method of supplementing the power output of a gas turbine systemhaving a compressor, a combustor case, a combustor, and a turbine,fluidly connected to each other, said method comprising: (i) providing asupplemental compressor, and a fueled engine; (ii) operating said fueledengine to drive said supplemental compressor to produce compressed airfrom said supplemental compressor and hot exhaust gas from said fueledengine; (iii) heating said compressed air with heat extracted from saidhot exhaust gas, thereby producing hot compressed air; and (iv)injecting said hot compressed air into said gas turbine systemdownstream of said compressor of said gas turbine system, therebyincreasing the mass flow of air therethrough and augmenting the poweroutput of said gas turbine system.
 2. The method of claim 1 wherein thestep of heating said compressed air with heat extracted from said hotexhaust gas is followed by the step of injecting said hot exhaust gasinto exhaust from said turbine.
 3. The method of claim 1 wherein thestep of operating said fueled engine to drive said supplementalcompressor to produce compressed air from said supplemental compressorincludes the step of cooling said compressed air received from anupstream stage of said supplemental compressor before delivering it toanother compression stage downstream of the upstream compressor stage.4. The method of claim 2 wherein the step of operating said fueledengine to drive said supplemental compressor to produce compressed airfrom said supplemental compressor includes the step of cooling saidcompressed air received from an upstream stage of said supplementalcompressor before delivering it to another compression stage downstreamof the upstream compressor stage.
 5. The method of claim 1 wherein thestep of operating said fueled engine to drive said supplementalcompressor to produce compressed air from said supplemental compressorincludes the step of storing a first portion of said compressed air inan air storage tank.
 6. The method of claim 5 wherein the step ofstoring a first portion of said compressed air in an air storage tank isfollowed by the step of releasing some of said first portion ofcompressed air from said air storage tank and mixing it with a secondportion of said compressed air.
 7. The method of claim 6 wherein thestep of storing a first portion of said compressed air in an air storagetank is preceded by the step of cooling said first portion of saidcompressed air.
 8. The method of claim 7 further including the step ofpumping a hydraulic fluid into said air storage tank when the pressureof said first portion of compressed air remaining in said air storagetank falls below a predetermined pressure.
 9. A method of supplementingthe power output of a gas turbine system having a compressor, acombustor case, a combustor, a turbine, a heat recovery steam generator,and a steam turbine fluidly connected to each other, said methodcomprising: (i) providing a supplemental compressor, and a supplementalengine powered by steam; (ii) operating said supplemental engine todrive said supplemental compressor to produce compressed air from saidsupplemental compressor and hot exhaust from said supplemental engine;and (iii) injecting said compressed air into said gas turbine systemdownstream of said compressor of said gas turbine system, therebyincreasing the mass flow of air therethrough and augmenting the poweroutput of said gas turbine system.
 10. The method of claim 9 whereinsaid supplemental engine is a steam engine, and the step of operatingsaid supplemental engine to drive said supplemental compressor toproduce compressed air from said supplemental compressor is followed bythe step of injecting said hot exhaust into said heat recovery steamgenerator.
 11. The method of claim 9 wherein the step of operating saidengine to drive said supplemental compressor to produce compressed airfrom said supplemental compressor includes the step of cooling saidcompressed air received from an upstream stage of said supplementalcompressor before delivering it to another compression stage downstreamof the upstream compressor stage.
 12. The method of claim 10 wherein thestep of operating said engine to drive said supplemental compressor toproduce compressed air from said supplemental compressor includes thestep of cooling said compressed air received from an upstream stage ofsaid supplemental compressor before delivering it to another compressionstage downstream of the upstream compressor stage.
 13. The method ofclaim 9 wherein the step of operating said engine to drive saidsupplemental compressor to produce compressed air from said supplementalcompressor includes the step of storing a first portion of saidcompressed air in an air storage tank.
 14. The method of claim 13wherein the step of storing a first portion of said compressed air in anair storage tank is followed by the step of releasing some of said firstportion of compressed air from said air storage tank and mixing it witha second portion of said compressed air.
 15. The method of claim 14wherein the step of storing a first portion of said compressed air in anair storage tank is preceded by the step of cooling said first portionof said compressed air.
 16. The method of claim 15 wherein furtherincluding the step of pumping a hydraulic fluid into said air storagetank when the pressure of said first portion of compressed air remainingin said air storage tank falls below a predetermined pressure.
 17. Amethod of supplementing the power output of a gas turbine system havinga compressor, a combustor case, a combustor, a turbine and a heatrecovery steam generator, fluidly connected to each other, said methodcomprising: (i) providing a auxiliary gas turbine having a supplementalcompressor and a supplemental turbine in addition to said gas turbinesystem; (ii) operating said supplemental compressor to producecompressed air from said supplemental compressor and hot exhaust gasfrom said supplemental turbine; and (iii) injecting a portion of saidcompressed air into said gas turbine system downstream of saidcompressor of said gas turbine system, thereby increasing the mass flowof air therethrough and augmenting the power output of said gas turbinesystem.
 18. The method of claim 17 wherein substantially all of thepower produced by the supplemental turbine is used to drive thesupplemental compressor. (JB Comment: Can we define “substantially all”as greater than x % and insert definition into specification?)
 19. Themethod of claim 18 further comprising the step of injecting said hotexhaust gas into exhaust from said turbine.
 20. An apparatus forsupplementing the power output of a gas turbine system having acompressor, a combustor case, a combustor, and a turbine, fluidlyconnected to each other, said apparatus comprising: (i) a supplementalcompressor to produce compressed air, said supplemental compressorhaving a compressed air outlet; (ii) a fueled engine to connected tosaid supplemental compressor to drive said supplemental compressor, saidfueled engine producing hot exhaust gas and having an exhaust outlet;and (iii) a recuperator having a first recuperator inlet, a secondrecuperator inlet, a first recuperator outlet, and a second recuperatoroutlet, said first recuperator inlet fluidly connected to saidcompressed air outlet, said second recuperator inlet fluidly connectedto said exhaust outlet, said first recuperator outlet fluidly connectedto said first recuperator inlet and fluidly connected to said gasturbine system downstream of said compressor of said gas turbine system,and said second recuperator outlet is fluidly connected to said secondrecuperator inlet and fluidly connected to said gas turbine systemdownstream of said turbine of said gas turbine system; wherein heat fromsaid hot exhaust gas is transferred to said compressed air in saidrecuperator prior to being injected into said gas turbine system. 21.The apparatus of claim 20 wherein said supplemental compressor is amultistage compressor, and each stage of said multistage compressor hasa stage inlet and a stage outlet.
 22. The apparatus of claim 21 furthercomprising an intercooler heat exchanger fluidly connected to at leastone of said stage inlets and at least one of said stage outlets to coolsaid compressed air received from one of said stage outlets prior todelivering said compressed air to one of said stage inlets downstreamthereof.
 23. The apparatus of claim 22 further comprising an air storagetank fluidly connected to said compressed air outlet of saidsupplemental compressor by a first conduit for storing a first portionof said compressed air.
 24. The apparatus of claim 23 further comprisinga mixer having a mixer inlet and a mixer outlet, said mixer inletfluidly connected to said air storage tank and said compressed airoutlet of said supplemental compressor, said mixer outlet fluidlyconnected to said mixer inlet, and said mixer outlet fluidly connectedto said first recuperator inlet between said compressed air outlet andsaid first recuperator inlet.
 25. The apparatus of claim 24 furthercomprising at least one valve fluidly connected between said air storagetank and said compressed air outlet of said supplemental compressor. 26.The apparatus of claim 25 further comprising a hydraulic fluid storagetank and a pump fluidly connected to said air storage tank and saidhydraulic fluid storage tank for pumping a hydraulic fluid between saidhydraulic fluid tank and said air storage tank.
 27. The apparatus ofclaim 26 further comprising a least one bypass valve fluidly connectedbetween one of said outlet stages of said supplemental compressor andone of said inlet stages of said supplemental compressor for bypassingsaid intercooler heat exchanger.
 28. The apparatus of claim 27 furthercomprising a least one transfer valve fluidly connected to said mixeroutlet and said first recuperator inlet for controlling the flow ofcompressed air between said mixer and said recuperator.
 29. An apparatusfor supplementing the power output of a gas turbine system having acompressor, a combustor case, a combustor, a turbine, a heat recoverysteam generator, and a steam turbine fluidly connected to each other,said apparatus comprising: (i) a supplemental compressor to producecompressed air, said supplemental compressor having a compressed airoutlet; and (ii) an engine powered by steam connected to saidsupplemental compressor to drive said supplemental compressor, saidengine producing hot exhaust and having an exhaust outlet.
 30. Theapparatus of claim 29 further comprising an air storage tank fluidlyconnected to said compressed air outlet of said supplemental compressorby a first conduit for storing a first portion of said compressed air.31. The apparatus of claim 30 further comprising a mixer having a mixerinlet and a mixer outlet, said mixer inlet fluidly connected to said airstorage tank and said compressed air outlet of said supplementalcompressor, said mixer outlet fluidly connected to said gas turbinesystem downstream of said compressor of said gas turbine system.
 32. Theapparatus of claim 31 further comprising at least one valve fluidlyconnected between said air storage tank and said compressed air outletof said supplemental compressor.
 33. The apparatus of claim 32 furthercomprising a hydraulic fluid storage tank and a pump fluidly connectedto said air storage tank and said hydraulic fluid storage tank forpumping a hydraulic fluid between said hydraulic fluid tank and said airstorage tank.
 34. The apparatus of claim 33 further comprising a leastone transfer valve fluidly connected to said mixer outlet and said gasturbine system downstream of said compressor of said gas turbine systemfor controlling the flow of compressed air between said mixer and saidgas turbine system.
 35. An apparatus for supplementing the power outputof a gas turbine system having a compressor, a combustor case, acombustor, and a turbine fluidly connected to each other, said apparatuscomprising: an auxiliary gas turbine having a supplemental compressor,supplemental combustor case, a supplemental combustor, and asupplemental turbine fluidly connected to each other, said supplementalcompressor connected to said supplemental turbine such that rotation ofsaid supplemental turbine drives said supplemental compressor andproduces compressed air, said supplement compressor having a compressedair outlet for diverting a first portion of said compressed air fromsaid auxiliary gas turbine prior to said compressed air entering saidsupplemental turbine; and a first conduit connecting said compressed airoutlet to said gas turbine system downstream of said compressor forinjecting said portion of compressed air into said gas turbine systemdownstream of said compressor of said gas turbine system, therebyincreasing the mass flow of air therethrough and augmenting the poweroutput of said gas turbine system.
 36. The apparatus of claim 35 whereinthe supplemental compressor and the supplemental turbine are sized suchthat substantially all of the power produced by the supplemental turbineis used to drive the supplemental compressor.
 37. The apparatus of claim36 further comprising a valve in said first conduit for controlling theflow of compressed air therethrough.
 38. The apparatus of claim 37further comprising second conduit connected to an outlet of saidsupplemental turbine and an outlet of said turbine of said gas turbinesystem, wherein a second portion of said compressed air flows throughsaid supplemental turbine, then through said second conduit, and theninto exhaust from said turbine of said gas turbine system.